The ISL97635A is a digitally controlled LED driver that

controls 6 channels of LED current for LCD backlight

applications. The ISL97635A is capable of driving typically

54 (6x9) pieces of 3.5V/30mA or 60 (6x10) pieces of

3.2V/20mA LEDs. The ISL97635A contains 6 channels of

voltage controlled current sources with typical currents

matching of ±1, which compensate for the non-uniformity

effect of forward voltages variance in the LED stacks. To

minimize the voltage headroom and power loss in the typical

multi-strings operation, the ISL97635A features a dynamic

headroom control that monitors the highest LED forward

voltage string and uses its feedback signal for output

regulation.

The LED dimming control can be achieved through a

SMBus, an external PWM, or a variable DC (analog light

sensor) input. SMBus controlled dimming allows 256 levels

each of PWM and DC current adjustments. The SMBus

PWM dimming frequency can be adjusted from 100Hz to

5kHz by an external capacitor. External PWM input allows up

to 20kHz audio noise free PWM dimming. The SMBus PWM

setting and an external PWMI signal can also be combined

to provide a dynamic PWM dimming that complies with

Intel’s DPST (Display Power Saving Technology)

requirement.

One or more channels can be selected sequentially in any

order allowing scrolling in RGB LED backlighting

applications.

The ISL97635A features extensive protection functions that

include string open and short circuit detections, OVP, OTP,

thermal shutdown and an optional input overcurrent

protection with master fault disconnect switch. The fault

conditions will be recorded in the Fault/Status register. There

are selectable short-circuit thresholds and the switching

frequency can be programmed between 600kHz and

1.2MHz.

Available in the 24 Ld 4mmx4mm QFN, the ISL97635A

operates from -40°C to +85°C with input voltage ranging

from 6V to 24V for high LEDs count applications.

Features

• 6 Channels

• 6V to 24V Input

• 34.5V Output Max

• Drive Maximally 54 (3.5V/30mA each) or 60 (3.2V/20mA

each) LEDs

• Current Matching ±1 Typ

• Dynamic Headroom Control

• Dimming Controls

- SMBus 8-Bit PWM Current Control

- SMbus 8-Bit DC Current Control

- External PWM Input up to 20kHz Dimming

- SMBus and External PWM DPST Dimming Control

- DC-to-PWM Dimming Control

• Protections

- String Open Circuit Detection

- String Short Circuit Detection with Selectable

Thresholds

- Over-Temperature Protection

- Overvoltage Protection

- Input Overcurrent Protection with Disconnect Switch

• 600kHz/1.2MHz Selectable fSW

• Selectable Channels Allows Scrolling Backlight

• 24 Ld (4mmx4mm) QFN Package

• Pb-Free (RoHS Compliant)

Applications

• Notebook Displays WLED or RGB LED Backlighting

• LCD Monitor LED Backlighting

• Automotive Displays LED Backlighting

• Automotive or Traffic Lighting